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So I've got a 94FD manual tranny that needs a new radiator now. I have a new Koyo # R1443 in hand. And I believe some silicone main engine coolant hoses. In reading up on this here, it seems it isn't exactly a drop in? What to look out for? BTW, it seems this radiator is also for the AT version as it has the AT cooler line inlets in it as well? Do I need to block off those inlets? Any advice as to what other fitment issues I may be facing? And what other lines need replacement-like to the fill tank, expansion tank? What and where to order them from? Thanks for any advice!
First off, the Koyo rad shouldn't have AT fittings. It should have a fitting for the AST hose and mounting points for the fans, though. If you see something different, post up a picture.
As far as parts on hand, I recommend new OEM radiator hoses, the silicone ones are hit and miss but the OEM hoses fit great and are of really good quality. Also use the OEM spring clamps, worm clamps don't work well on coolant hoses, they can cut into the hose and also many times aren't tight enough so they leak.
If you have the stock AST it may be worth replacing the hoses if they look bad but those are easy to get to at any time.
There are 2 rubber feet that go around the pegs on the bottom of the radiator and fit into the holes in the chassis. Those are worth replacing, they aren't much from Mazda.
Get 1 gallon of Prestone green antifreeze and 1 gallon of distilled water from the grocery store. If you don't have a Lisle funnel now is the time to get one, that makes adding coolant and burping the air out so much easier.
Banzai Racing has a great how-to on installing the Koyo -
Thanks Dale! Reviewed the info. Yes, this rad does NOT have AT line fittings, those are for the fans, my mistake. Also does not have fitting on top like some pics on that thread (for air release?). I’d like to replace the side foam, ideas where to find? I followed the SM, replacing from beneath. Pita. Getting to the upper left nut on radiator is difficult because AC dryer is in the way. SM does not have you removing the IC or dryer plastic surround, fwiw. I am concerned about that condenser bracket, why does it need to be ‘flipped’? And is the ‘burping’ process in the SM?
The Koyo is thicker than stock, flipping the bracket gives more room for fitment.
I've always done radiator installs mainly from up top - remove IC, battery tray, etc.
I don't think the shop manual really has a burping procedure. Put the Lisle funnel on wherever your radiator cap is - AST if you are mostly stock. Fill up with the car off until it won't take any more and isn't burping up any more air bubbles. If you have the coolant those that's going to the throttle body you can pop that off, that helps give air a path to leave, just be ready to put the hose back on when coolant comes out there. Start and run the car and keep the funnel half full. Once the thermostat opens you'll get some more air and possibly some boiling. After 15 minutes or so of idle, shut the car off and let things cool back down, keep the funnel with coolant in it so the system pulls coolant in as it cools and contracts. Let it fully cool down, then put caps back on and go for a drive. For the next few days check the coolant level when stone cold and top off if necessary, you may have a tiny amount of air still at the top.
Thanks, got the lisle funnel. I have an aftermarket AST, but isn’t it best to attach to pump cap at thermostat? More volume. Also heater on or off while ‘burping’. I’ve heard both ways.
You have to hook the Lisle funnel to whatever has the hose going to the overflow tank, in this case the AST. That closes the overflow tank out of the equation.
But, you may want to use the other cap for some of the initial filling. Filling through the AST will go slowly with the small hoses. Also I can't remember the last time I filled a car with an AST
The Koyo is thicker than stock, flipping the bracket gives more room for fitment.
I've always done radiator installs mainly from up top - remove IC, battery tray, etc.
I don't think the shop manual really has a burping procedure. Put the Lisle funnel on wherever your radiator cap is - AST if you are mostly stock. Fill up with the car off until it won't take any more and isn't burping up any more air bubbles. If you have the coolant hose that's going to the throttle body you can pop that off, that helps give air a path to leave, just be ready to put the hose back on when coolant comes out there. Start and run the car and keep the funnel half full. Once the thermostat opens you'll get some more air and possibly some boiling. After 15 minutes or so of idle, shut the car off and let things cool back down, keep the funnel with coolant in it so the system pulls coolant in as it cools and contracts. Let it fully cool down, then put caps back on and go for a drive. For the next few days check the coolant level when stone cold and top off if necessary, you may have a tiny amount of air still at the top.
Dale
On my close to OE coolant-hose setup, the AST cap (pressure relief) is several inches lower than the thermostat housing fill (non-relief) cap. So, IMO, it's a lot better to fill from the upper cap. Filling from the AST location means you can't get as much coolant in or air out before it overflows. I initially fill from the top cap but with the AST cap off. When the coolant gets to that level I reinstall the AST cap and continue to fill until coolant comes out the coolant hose that's going to the throttle body.
This makes sense. Again, I haven't filled an AST car in a long time.
May be worth removing the hose going to the overflow tank and capping that nipple on the AST while doing the fill. The idea with the funnel is that you eliminate the overflow during the fill operation.
This all may be overkill since the radiator cap will only open under pressure and the system won't pressurize while the funnel is attached.
Yup, it would fill faster thru the themo fixed cap, I'll do that first then attach funnel. Will also make sure there is some coolant in the plastic dipstick filler tank, and the metal aftermarket AST I have as well.
Issue: when I installed the Koyo radiator yesterday, with the right front AC condenser bracket flipped over (I question if this was done correctly-seems weird, I had to bend the bracket tab for the bracket to fit squarely against the frame, and it flipped the welded nut downward, so condenser screws thru the bracket nut first!), it spaced the condenser quite a bit back from the radiator at the top compared to the left side at the front top, so much so that I cannot get the right rear condenser bracket to fit up against the frame anymore-to do so, the condenser would hit the radiator and rub badly at the bottom. I inspected the sway bar/radiator brackets, and from what I can see, they do not look damaged or bent to my scrutiny, but somehow the bottom of the condenser now contacts the radiator? I plan on putting a spacer behind that condenser bracket with a longer screw so that it does not mount so close at the bottom. What would cause this to happen? The stock radiator and condenser mounted fine with the same sway bar brackets. It's almost like the radiator is angled strangely for this to occur.
I found that installing the Koyo N-Flo radiator was much easier once I did it from the bottom. If you've properly flipped the condenser bracket as Banzai-Racing shows in his thread, you shouldn't have any radiator/condenser contact.
If you remove the sway bar and the mounts you can more easily slide the Koyo in as the FSM recommends doing. You can then re-install the brackets and sway bar afterwards. The bending of the brackets is VERY difficult to see with naked eye btw. Usually it is only after getting new ones that you can notice what is wrong. I opted for new ones during my install process because well.. they ended up being bent a little bit.
In any event, if you follow the Banzai-Racing thread you shouldn't have any further issues. I too posted in that thread!
In this picture you can see how close the two are yet there is zero contact.
Last edited by twinturborx7pete; 04-19-21 at 12:34 PM.
Thanks all for the help, I got her done and all so far appears to be 'well'. I do note that at the AC condenser at the right upper side, the spacing from the radiator isn't the same distance as the other 3 mounting points, mostly because of the 'flipped' upper pax side radiator bracket, I suppose. I had to fashion a spacer behind a longer bolt to make that condenser position mount securely. I used foam insulation (usually used for pipes) to block off the sides of the radiator to the structure to block air leakages and improve full airflow thru radiator without air bypassing it.
This is such a good thread but for anyone struggling with the ac bracket flip, it wasn't a perfect fit for me. On the left is the original Banzai photo. On the right is mine, where you can see the bolt hole didn't line up. But if you look very closely you can see that the rubber grommet on the Banzai photo is set a few millimeters north of normal (notice under the bottom of the grommet you can see the wear mark where it originally sat). Once I realized that the grommet needed to be relocated I was in business. I pulled the rubber grommet out and stole another millimeter or so by pressing it back as close to the top of the arm as possible. This allowed me to get my screw started at a 10 degree angle or so and get a socket on it. Once the screw was started I was able to squeeze the bracket into alignment while tightening and then it all came together.
5 minutes next time. 75 minutes the first time
Fully attached, side view, my grommet ended up smooshed a bit off center. Not sure if this is how everybody's looks but it's solid. From the photo it appears that a nicer fit might be possible by shaving off a bit of the bracket lip.
04-15-21, 04:40 PM
Radiator replacement? With Koyo R1443
